In order to adequately determine the reserves of gas or hydrocarbons contained in a reservoir, it is useful to establish grids (or meshed models for example) of reservoirs, for example based on 3D seismic interpretation of the underground or based on geological knowledge of drilling or operating wells.
These models must be determined in order to represent the actual underground containing the reservoir as truly as possible.
In the oil industry, a test well can make it possible to better understand the characteristics of the reservoir wherein the hydrocarbons are trapped. Most often, a test well comprises the opening (“draw down” phase) and/or the closing (“build up” phase) of the well in question: the variations in flow and pressure over time are then recorded.
One of the objectives of a test well can be to determine the capacity of the reservoir for the production of hydrocarbons, such as oil or natural gas.
Another objective of such a test can be descriptive, i.e. make it possible to determine the geometries and certain characteristics of the reservoir (i.e. permeability of the rock, presence of limits, connectivity of the wells between them, etc.).
“Dynamic modelling stresses” refers to all of the information determined using these test wells (e.g. volume connected to the well, presence of limits in the reservoir and associated distance(s), flow property of the fluids to the well, permeability of the rock, connectivity etc.).
In order to satisfy the dynamic modelling stresses, reservoir engineers or geologists most often determine a large number of “candidate” models using known methodologies (as, for example, the one described in patent application FR1257649, for determining channels) then eliminate the models that do not satisfy these dynamic stresses (with possibly a given tolerance margin): this approach can be considered as an a posteriori (or empirical) approach.
However, such methods are not free of defects.
Indeed, only a small number of models (bearing a possible share of randomness) systematically satisfy the dynamic stresses.
As such, the full calculation of the models which in the end will be set aside can consume calculation resources and substantially slow down the determination of a suitable model.
In addition, this approach can be complex in particular in order to verify certain dynamic stresses such as the “non-connectivity” between two wells as the combinatorics can be excessively complicated.
There is therefore a need to take the dynamic stresses into account as far upstream as possible when determining the geological model in order to optimise the calculation resources. In addition, this taking into account can make it possible to improve the pertinence and the reliability of the geological models determined.
This invention as such improves the situation.